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Optimize Object::cast_to by assuming no virtual and multiple inheritance, gaining 8x throughput over dynamic_cast.

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Add `-Wvirtual-inheritance` to compiler warnings as a sanity check.
This commit is contained in:
Lukas Tenbrink
2025-03-27 15:39:53 +01:00
parent 594d64ec24
commit dd9dc75a83
3 changed files with 33 additions and 3 deletions
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7
SConstruct
View File

@@ -860,7 +860,12 @@ else: # GCC, Clang
common_warnings = []
if methods.using_gcc(env):
common_warnings += ["-Wshadow", "-Wno-misleading-indentation"]
common_warnings += [
"-Wshadow",
"-Wno-misleading-indentation",
# For optimized Object::cast_to / object.inherits_from()
"-Wvirtual-inheritance",
]
if cc_version_major < 11:
# Regression in GCC 9/10, spams so much in our variadic templates
# that we need to outright disable it.

27
core/object/object.h
View File

@@ -440,6 +440,9 @@ public:
} \
\
protected: \
virtual bool _derives_from(const std::type_info &p_type_info) const override { \
return typeid(m_class) == p_type_info || m_inherits::_derives_from(p_type_info); \
} \
_FORCE_INLINE_ static void (*_get_bind_methods())() { \
return &m_class::_bind_methods; \
} \
@@ -768,6 +771,12 @@ protected:
mutable VirtualMethodTracker *virtual_method_list = nullptr;
#endif
virtual bool _derives_from(const std::type_info &p_type_info) const {
// This could just be false because nobody would reasonably ask if an Object subclass derives from Object,
// but it would be wrong if somebody actually does ask. It's not too slow to check anyway.
return typeid(Object) == p_type_info;
}
public: // Should be protected, but bug in clang++.
static void initialize_class();
_FORCE_INLINE_ static void register_custom_data_to_otdb() {}
@@ -787,12 +796,26 @@ public:
template <typename T>
static T *cast_to(Object *p_object) {
return p_object ? dynamic_cast<T *>(p_object) : nullptr;
// This is like dynamic_cast, but faster.
// The reason is that we can assume no virtual and multiple inheritance.
static_assert(std::is_base_of_v<Object, T>, "T must be derived from Object");
if constexpr (std::is_same_v<std::decay_t<T>, typename T::self_type>) {
return p_object && p_object->_derives_from(typeid(T)) ? static_cast<T *>(p_object) : nullptr;
} else {
// T does not use GDCLASS, must fall back to dynamic_cast.
return p_object ? dynamic_cast<T *>(p_object) : nullptr;
}
}
template <typename T>
static const T *cast_to(const Object *p_object) {
return p_object ? dynamic_cast<const T *>(p_object) : nullptr;
static_assert(std::is_base_of_v<Object, T>, "T must be derived from Object");
if constexpr (std::is_same_v<std::decay_t<T>, typename T::self_type>) {
return p_object && p_object->_derives_from(typeid(T)) ? static_cast<const T *>(p_object) : nullptr;
} else {
// T does not use GDCLASS, must fall back to dynamic_cast.
return p_object ? dynamic_cast<const T *>(p_object) : nullptr;
}
}
enum {

2
scene/gui/dialogs.compat.inc
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@@ -30,6 +30,8 @@
#ifndef DISABLE_DEPRECATED
#include "scene/gui/line_edit.h"
void AcceptDialog::_register_text_enter_bind_compat_89419(Control *p_line_edit) {
register_text_enter(Object::cast_to<LineEdit>(p_line_edit));
}